KR20190128255A - Damascene template for directed assembly and transfer of nanoelements - Google Patents

Abstract

The damascene templates have two-dimensionally patterned raised metal features disposed on a lower conductive layer extending across the substrate. The templates are photographically flat throughout, and the patterned conductive features build micron-scale and nanometer-scale patterns for the assembly of nanoelements into nanoscale circuits and sensors. Templates are made using microfabrication techniques, along with chemical mechanical polishing. These templates are compatible with a variety of direct assembly techniques, including electrophoresis, and provide essentially 100% efficient assembly and transfer of nanoelements in continuous operation cycles. Templates can be used repeatedly thousands of times for the transfer of patterned nanoelements, with minimal or no damage, and the transfer process does not include intermediate processes between cycles. The assembly and transfer processes used are performed at room temperature and at room pressure, thus handling low cost, high speed device production.

Description

DAMASCENE TEMPLATE FOR DIRECTED ASSEMBLY AND TRANSFER OF NANOELEMENTS

This application claims priority to US Provisional Application No. 61 / 557,594, filed November 9, 2011, entitled "Damascene Template for Directed Assembly and Transfer of Nanoelements," which is hereby incorporated by reference in its entirety. Are integrated.

The present invention was developed with financial support from Grant No. EEC-0832785 and Grant No. 0425826 from the National Science Foundation. US information has certain rights in the present invention.

The assembly of nanoelements on the template using precise alignment and orientation, followed by the transfer of nanoelements to the receiving substrate, is expected to accelerate the large scale production of nanoscale devices. However, with minimal degradation, the absence of highly versatile and reusable templates for high-throughput direct assembly and transfer has hampered any progress.

Various templates fabricated through bottom-up or top-down processes have been used to assemble nanoelements to achieve the desired architectures [1-3]. The template-guided fluid assembly process can handle a variety of nanoelements and can result in high assembly density, yield and uniformity [4-6]. However, the assembly process is very slow and therefore not scalable. On the other hand, electrophoretic assembly involves assembling nanomaterials having surface charges on a conductive surface over large areas (wafer scale) in a short time period [7-10]. When nanoelements are assembled on an electrode that is photographically patterned by electrophoresis through interconnected microscale and nanoscale features, the assembly is not uniform due to differences in potential drop in various regions of the electrode. Previously, this obstacle was avoided by using so-called "trench templates", in which a lithographically-defined polymer pattern lies on a uniform conductive layer that guides the assembly to the desired locations. Whenever nanoelements assembled in these trench templates need to be transferred to a receiving substrate, the polymer must be removed, thereby limiting the use of the template to a single assembly and transfer cycle [11].

Transferring assembled nanoelements from one substrate to another, while maintaining their respective two-dimensional order, is a fairly difficult process that requires an in-depth knowledge of the interaction energy between different materials and nanoelements. Successful achievement of aligned nanoelement transfer onto flexible substrates will enable the production of various types of new devices such as thin film transistors, gas sensors, and biosensors [12-14]. Although the transfer of nanoelements using a template sacrificial layer (eg, SiO ₂ layer) has been demonstrated for transfer onto rigid substrates as well as flexible substrates and has proven to have high transfer efficiency, such templates cannot be reused [15] . Intermediate sacrificial films such as Revalpha thermal tape and PDMS for transferring nanoelements to receiving substrates have also been explored, but they introduce additional steps and thus lead to a complex fabrication process leading to higher production costs. 17].

The present invention provides highly reusable, photographically flat damascene templates, and methods for nanoelements assembled onto damascene templates using electrophoresis. The present invention also provides methods for transferring assembled nanoelements from damascene templates onto flexible substrates using a “transcription printing” method. Transfer printing methods can be used to fabricate microscale and nanoscale structures, including combinations of microscale and nanoscale structures on a single chip, without the need for intermediate films [18-19].

The inventors have designed and fabricated photographically flat damascene templates with submicron features using microfabrication techniques in combination with chemical mechanical polishing (CMP). These templates are designed to be compatible with a variety of direct assembly techniques including electrophoresis, with essentially 100% assembly and transfer yield for different nanoelements such as single-walled carbon nanotubes and nanoparticles. These templates can be used thousands of times repeatedly for transfer, with or without minimal damage, and the transfer process does not include intermediate processes between cycles. The assembly and transfer processes used are performed at room temperature and at room pressure, thus handling low cost, high speed device production.

One aspect of the invention is a damascene template for electrophoretic assembly and transcription of patterned nanoelements. The template substantially comprises a planar substrate, a first insulating layer, an optional adhesive layer, a conductive metal layer, a second insulating layer, and an optional hydrophobic coating. The first insulating layer is disposed on the surface of the substrate. The adhesive layer, if present, is disposed on the surface of the first insulating layer opposite the substrate. The conductive metal layer is disposed on the surface of the first insulating layer, on the opposite side of the first insulating layer, or on the surface of the first insulating layer, on the opposite side of the substrate, if there is no adhesive layer. The second insulating layer is disposed on the surface of the conductive metal layer on the opposite side of the adhesive layer, or on the opposite side of the first insulating layer if there is no adhesive layer. The hydrophobic coating is selectively disposed on the exposed surfaces of the second insulating layer, opposite the conductive metal layer; The hydrophobic coating is not on the exposed surfaces of the conductive metal layer. The conductive metal layer is continuous over at least one area of the substrate, or in some embodiments over the entire substrate. Within this region of the conductive metal layer, the conductive metal layer has raised features in a two-dimensional microscale or nanoscale pattern that interrupts the second insulating layer, substantially reducing the spaces between the raised features of the second insulating layer. Filled up. The exposed surfaces of the raised features and the exposed surfaces of the second insulating layer are essentially coplanar due to planarization by the chemical mechanical polishing procedure.

Another aspect of the invention is a nanoelement transcription system for the transfer of patterned nanoelements by nanoimprinting. The system includes the damascene template described above, and a flexible polymer substrate for accommodating the plurality of nanoelements. In some embodiments, the system also includes a thermally controlled imprint device for applying pressure between the damascene template and the flexible polymer substrate at a selected temperature above ambient temperature.

Another aspect of the invention is a method of making the damascene template described above. The method includes the following steps:

(a) providing a substantially planar substrate;

(b) depositing a first insulating layer on the surface of the substrate;

(c) optionally, depositing an adhesive layer on said first insulating layer;

(d) depositing a conductive metal layer on the adhesive layer or on the first insulating layer if the adhesive layer is absent;

(e) depositing a lithographic resist layer on the conductive metal layer;

(f) performing lithography to produce voids in the resist layer in a two-dimensional pattern, whereby the surface of the conductive metal layer is exposed at the voids;

(g) etching the exposed surface of the conductive metal layer;

(h) removing the resist layer, leaving the entire surface of the conductive metal layer exposed, wherein the conductive metal layer includes raised features in a two-dimensional pattern;

(i) depositing an insulating material to cover the conductive metal layer including the raised features;

(j) removing the insulating material and a portion of the raised features by a chemical mechanical polishing method, whereby the raised features and insulating material are planarized to expose the raised features of the two-dimensional pattern Left exposed, the exposed surfaces being coplanar with each other and with the exposed surfaces of the insulating material; And

(k) optionally silanically exposing the exposed surfaces of the insulating material using a hydrophobic coating of alkyl silanes.

In some embodiments, the method further comprises the following steps:

(l) chemically cleaning the exposed surfaces of the raised features of the conductive metal layer without substantially removing the hydrophobic coating on the insulating layer.

Yet another aspect of the present invention is a method of forming a patterned assembly of nanoelements on a damascene template. The method includes the following steps:

(a) providing a damascene template as described above;

(b) dipping the damascene template into the liquid suspension of nanoelements;

(c) in the liquid suspension, applying a voltage between the conductive metal layer of the damascene template and the counter electrode, such that nanoelements from the suspension are formed of raised features of the conductive metal layer of the damascene template. Selectively assembled onto exposed surfaces and not assembled onto exposed surfaces of the second insulating layer of the damascene template;

(d) withdrawing the damascene template and the assembly of nanoelements from the liquid suspension while continuing to apply the same voltage as in step (c); And

(e) drying the damascene template.

Another aspect of the invention is a method of transferring a two-dimensional patterned assembly of nanoelements onto a flexible polymer substrate. The method includes the following steps:

(a) providing a patterned assembly of nanoelements on a damascene template, such as produced by the method described above, and a flexible polymer substrate;

(b) contacting and applying the patterned assembly of nanoelements to the flexible polymer substrate, whereby the patterned assembly of nanoelements is transferred onto a flexible patterned substrate. In some embodiments, step (b) is performed at a temperature above the glass transition temperature of the flexible polymer substrate.

Yet another aspect of the present invention is a method of assembling and transferring a two-dimensional patterned assembly of nanoelements onto a flexible polymer substrate. The method includes the following steps:

(a) providing a nanoelement transfer system as described above and a liquid suspension of nanoelements;

(b) performing electrophoretic assembly of nanoelements from the liquid suspension onto the damascene template according to the method described above, to yield a patterned assembly of nanoelements on a damascene template; And

(c) contacting and applying the patterned assembly of nanoelements to the flexible polymer substrate, whereby the patterned assembly of nanoelements is transferred onto a flexible patterned substrate. In some embodiments, the contacting step is performed at a temperature above the glass transition temperature of the flexible polymer substrate.

1 (a) shows a schematic diagram of a damascene template fabrication process. The resist was spun onto an Au / Si substrate and nanolithography was used to define the patterns. Patterned Au was partially etched and plasma-enhanced chemical vapor deposition (PECVD) oxide (SiO ₂ ) was deposited on the Au surface. Excess SiO ₂ was removed by a chemical mechanical polishing (CMP) process until the top surfaces of the Au raised features were revealed. Inset shows an artificially colored, cross-sectional scanning electron microscopy (SEM) micrograph showing that the metal electrode (elevated metal features) is at the same height as the SiO ₂ height. 1 (b) shows an optical image of a 3 inch damascene template with high-resolution SEM images as insets. 1 (c) shows the electric field strength results simulated at 2.5V and pH 10.8 as a function of dishing amount. The electric field strength near the SiO ₂ surface has about the same magnitude as the electric field strength of the Au electrode, but as the amount of dishing increases, the non-uniformity of the electric field increases from the edge of the electrode to the center. The inset figures at the bottom are plan and cross-sectional views of electric field strength contours at 25 nm dishing amount. The contours indicate that higher electric field strength is produced on the electrode edges. 1 (d) shows a schematic representation of a cross-sectional view of an embodiment of the damascene template of the present invention. The structures shown are: substrate 10, first insulating layer 15, adhesive layer 20, conductive metal layer 30-raised features 40, second insulating layer 50, and hydrophobic coatings. Has (60).
2 is a schematic of an assembly and transfer process using damascene templates. The insulating (SiO ₂ ) surface of the damascene template is selectively coated with a hydrophobic self-assembled monolayer (SAT) of octadecyltrichlorosilane (OTS). Using electrophoresis, the nanoelements are assembled on the electrodes of the damascene template, and then they are transferred to the flexible substrate using a printing transfer method. After the transfer, the template is prepared for the next assembly and transfer cycle.
3 (a) shows a SEM micrograph viewed from above of silica particles assembled on a damascene template. The voltage applied during assembly was 2V and the withdrawal speed was 1 mm / minute. 100 nm silica particles were assembled only on the edge of the gold electrode (shown in FIG. 1 (b)). FIG. 3 (b) is an SEM micrograph of the results of a typical high-density 100 nm silica nanoparticle assembly for assembly at a draw rate of 2.5 V and 5 mm / min. Despite the increase in withdrawal, the assembly of nanoparticles was uniform. 3 (c) shows 50 nm PSL particles assembled on the gold electrode surface at high density, using the same conditions as for the 100 nm silica nanoparticles. 3 (d) shows 100 nm fluorescent silica particles assembled on composite 2D patterns, demonstrating the versatility of the damascene template. Inset is a fluorescence microscopic image of the assembled silica particles. FIG. 3 (e) shows an SEM image of a highly dense and organized single-walled carbon nanotube (SWNT) assembly achieved at an applied voltage of 2.5V while the draw rate is maintained at 5 mm / min. 3 (f) shows SEM micrographs of large scale assembled SWNTs showing uniformity.
4 (a) shows SEM micrographs of the damascene template after transfer and FIG. 4 (b) shows the transfer substrate with the transferred SWNTs. FIG. 4C shows an optical micrograph of highly organized SWNT arrays with metal electrodes on a PEN film. Inset figures are AFM images and SEM micrographs of transferred SWNTs with two metal electrodes. AFM (atomic force microscopy) profile indicates that there are no indentations created on the transfer substrate. 4 (d) shows IV characteristics for various channel lengths and fixed channel widths (2.4 μm). 4 (e) shows the change in resistance of the SWNT channel (2.4 μm wide and 30 μm long) as a function of the bending radius of the PEN substrate.
5 (a) shows a schematic of a conventional template used for the electrophoretic assembly. In this template, nanowire electrodes are connected to a micron scale electrode, which in turn is connected to a large metal pad, and a potential is applied through the large metal pad. A schematic of a damascene template is shown in FIG. 5 (b), where both micron scale electrodes and nanometer scale electrodes are connected to a metal sheet under an insulating layer. Corresponding equivalent resistor circuits are shown in both figures, where Rm is the resistance introduced due to the micron scale electrode and Rn is the resistance introduced due to the nanoscale electrode, while Rs is the resistance introduced due to the solution to be. In Fig. 5 (c), SEM micrographs of conventional nanoparticle assembly results obtained for the configuration shown in Fig. 5 (a) are shown. Nanoparticles were assembled only on micron scale electrodes and not on nanoscale electrodes connected to the micron scale electrodes.
6 (a) shows the electric field simulation results for various thicknesses of the electrode protruding from the insulating surface. As the electrode protrusion height increases, the non-uniformity of the electric field strength over the width of the electrode increases dramatically, resulting in inconsistent assembly across the electrode. In Fig. 6 (b), the electric field contour for the conventional template shown in Fig. 5 (a) is shown. Regardless of the thickness of the electrode, there is still a non-uniformity of electric field strength.
FIG. 7 (a) shows AFM and SEM images of damascene templates with metal electrodes protruding over the insulating surface by about 40 nm. 7 (b) shows the AFM morphology of the flexible PEN substrate after transfer. Concave structures similar to those of the template appear on the PEN substrate; The concave structures are about 40 nm deep.
8 shows SEM micrographs from above of damascene templates after assembly. The damascene templates shown were not treated with the OTS SAM layer. FIG. 8 (a) shows the nanoparticle assembly and FIG. 8 (b) shows the SWNT assembly. Nanoelements were not specifically assembled onto metal electrodes, but were also found on insulators.
9 shows contact angle measurements of OTS SAM coated metallic and insulating surfaces before and after treatment with a Pirana solution. 9 (a) and 9 (b) correspond to OTS SAM-coated SiO ₂ surfaces (second insulating layer) before and after pyrana solution treatment, respectively. The contact angle remained the same, establishing the fact that the OTS SAM layer remained unchanged. 9 (c) and 9 (d) show the OTS SAM-coated gold surface before and after pyrana solution treatment, respectively. A flat wafer, with a 150 nm thick layer of gold sputtered onto the wafer, was used for these measurements, instead of the patterned substrate. After the piranha treatment, the contact angle drastically decreased, indicating that the OTS SAM layer was removed.
FIG. 10 shows SEM micrographs seen from above of the damascene template after SWNT assembly, for various applied potentials: FIG. 10 (a) 1.5V; 10 (b) 2V; Fig. 10 (c) 2.5V and Fig. 10 (d) 3V. The rest of the assembly parameters remained constant. As can be seen from the images, the assembly efficiency on the metal electrode increases as a function of the applied electric field, and above the threshold, the SWNTs begin to assemble everywhere including the insulator.
FIG. 11 shows the SEM micrographs seen from above of the damascene template after SWNT assembly, for various withdrawal rates: FIG. 11 (a) 3 mm / min; (B) 5 mm / min; (C) 10 mm / min, and FIG. 11 (d) 15 mm / min. The rest of the assembly parameters remained constant. As can be seen from the images, as the withdrawal speed increases, the efficiency of the assembly on the metal electrode decreases, indicating the effect of the removal moment acting on the SWNTs during withdrawal.
12 shows a plot of contact angle measurements of OTS SAM coated SiO ₂ surfaces as a function of the number of assembly and transfer cycles. The slope of the linear fit, which indicates the firmness of the damascene template when withstanding the wear of multiple assemblies and transfer cycles, is ˜−0.18.
FIG. 13 shows the SEM micrographs seen from above of the damascene template after the transfer of SWNTs for various temperatures during transfer: FIG. 13 (a) 135 ° C .; 13 (b) 150 ° C .; And (c) 160 ° C. The rest of the transcription process parameters remained constant. As can be seen from the images, the transfer efficiency (absence of SWNTs on the metal electrode after the transfer) increases with increasing temperature, and ~ 100% transfer results in a flexible substrate (PEN) —the SWNTs are the flexible substrate (PEN). ) Is achieved at process temperatures higher than the Tg (155 ° C.).
14 shows a plot of resistance measured as a function of various bending radii. Inset shows the optical images of the experimental setup used to measure electrical characteristics at the desired bending radius.

The present invention provides methods for fabricating photographically flat damascene templates for assembly and transfer of nanoelements. Patterned assemblies of nanoelements, such as nanoparticles and carbon nanotubes, can be created on damascene templates and transferred to desired locations on the receptor substrate, so that high density and good uniformity of the patterned nanoelements can be achieved. Comes out. Transfer of assembled SWNTs or other nanoelements onto a flexible substrate can be performed without any intermediate steps and without the need for sacrificial films. The damascene templates of the present invention are reusable and can be used in high speed assembly and transfer processes. In addition, the damascene templates of the present invention are compatible with various types of nanoelements. The products and methods of the present invention can provide rapid advances in high speed manufacturing of flexible devices such as electrical and optical devices such as display devices and strain gauges, as well as biosensors and chemical sensors.

A schematic illustration of the damascene template fabrication process is shown in FIG. 1 (a). Initially, a metallic layer (eg Au or W) is deposited on the electrically insulating substrate and lithography is performed to produce the desired pattern for the nanoelement assembly. Subsequently, partial etching of the metallic layer is performed to form raised features with dimensions on the micrometer and / or nanometer scales. The raised features protrude above the rest of the plane of the metallic conductive layer. A thick layer of insulating material (eg, SiO ₂ or SiN ₄ ) is blanket deposited on these patterned structures. Then, a chemical mechanical polishing (CMP) process is performed, until the insulating material is essentially coplanar with the top surfaces of the raised metal features, and the top surfaces of the raised metal features are over or over the substrate. The insulating material is removed until it is coplanar with each other over the portion.

Thus, the resulting damascene template has nano / micro features connected by a conductive film under the insulator (second insulating layer), such that the entire substrate, or all of the micro / nano structures on the desired area of the substrate, are the same during the electrophoretic assembly. It is possible to have a potential. Preferred materials are gold for metallic layers and PECVD-deposited silicon dioxide for insulating layers.

Figure 1 (d) shows a cross-sectional view of a damascene template embodiment of the present invention. Substrate 10 is a base layer of an electrically insulating material such as silicon or polymer. The substrate is essentially planar, or generally planar, on at least one surface, and in some embodiments is substantially rigid, but in other embodiments may be flexible and bent to conform to the desired shape. The substrate may have any size or shape desired for a particular application, but generally has a thickness of about 1 μm to about 10 μm, or about 100 μm or less, or about 1000 μm or less, and about 0.005 mm 2 Or more, having a surface area of up to several cm 2 on the planar surface. The substrate can be made from organic insulating materials including silicon, silicon dioxide, epoxys and organic polymers including liquid crystal polymers, or photoresist material such as SU-8. The first insulating layer 15 is a layer of insulating material (eg, SiO ₂ , SiN ₄ , or polymer) that is deposited or induced to form on the surface of the substrate, and a conductive layer will be deposited on the surface and the nano The elements will be assembled. The thickness of the first insulating layer is, for example, about 10 nm to about 10 μm, about 20 nm to about 1 μm, or about 30 nm to about 500 nm, or about 5 nm to about 500 nm, or about 40 nm to about 250 Nm, or about 50 nm to about 100 nm. The first insulating layer is generally planar in structure and extends over the entire substrate layer or a portion of the substrate layer. The first adhesive layer prevents short circuits from the conductive layer to the substrate during the electrophoretic assembly. The adhesive layer 20 is an optional layer deposited on the first insulating layer. The adhesive layer provides improved adhesion of the conductive layer to the first insulating layer, so that the conductive layer remains in place when voltage is applied to the conductive layer during the electrophoretic assembly. Suitable materials for the adhesive layer include chromium, titanium, titanium dioxide, titanium nitride, tantalum, tantalum nitride, tungsten, and combinations thereof. The thickness of the adhesive layer can be, for example, about 3 nm to about 50 nm. Conductive layer 30 is a conductive metal layer deposited on an adhesive layer (if present) or on a first insulating layer (in embodiments without adhesive layer). Suitable materials for the conductive layer include metals such as gold, silver, tungsten, aluminum, titanium ruthenium, copper, and combinations or alloys thereof. The conductive layer properties are of two parts: (i) a planar base layer (thickness of about 50 nm to about 100 μm), and (ii) extending above the plane of the base layer (eg, from about 10 nm to about 10 μm in height). ), A plurality of raised features 40 having electrical continuity with each other through the base layer of the conductive layer. The second insulating layer 50 is initially deposited over the entire conductive layer, including raised features, and then planarized by chemical mechanical polishing, so that the exposed surfaces of the raised features and the top of the second insulating layer Make it coplanar. The thickness of the second insulating layer can be, for example, about 10 nm to about 10 μm, and is generally approximately equal to the height of the raised metal features. In some embodiments, the thickness of the second insulating layer and the raised features is the same within +/− 1 μm, 100 nm, 10 nm, or even 5 nm or 2 nm. The second insulating layer fills the spaces between the raised features and provides electrical insulation to those areas that block the assembly of nanoelements during the electrophoretic assembly. Suitable materials for the second insulating layer include SiO ₂ , SiN ₄ , Al ₂ O ₃ , organic polymers, and combinations thereof. In order to further block the nanoelement assembly in the insulated zones, such zones are preferably coated with a hydrophobic coating 60. The hydrophobic coating is preferably a self-assembled monolayer (SAM) of alkyl silane (covalently bonded to SiO ₂ if the material is used in the second insulating layer). The silane may be, for example, octadecyltrichlorosilane, or may be a similar silane having an alkyl chain of about 8-24 carbons in length. Although the thickness may also exceed one molecule, the preferred thickness of the hydrophobic coating is one molecule. The purpose of the hydrophobic coating is to prevent the assembly of nanoelements on the exposed surface of the second insulating layer; As such, the hydrophobic coating makes the exposed surface of the second insulating layer hydrophobic, selectively bonds to the second insulating layer and preferably exposes the exposed surface of the conductive layer, wherein the nanoelements will be assembled. Need only be unbonded. The hydrophobic coating has a contact angle of 90 ° to 110 °, preferably about 100 °. In contrast, the exposed metal conductive layer surface has a contact angle of 15 ° to 21 °, preferably about 18 °.

Fabrication techniques for making the damascene template of the present invention are known to those skilled in the art. Such techniques such as micropatterning and nanopatterning can be performed by e-beam lithography, photolithography, and nano-imprint lithography. Deposition of metals may be performed by sputtering, chemical vapor deposition, or physical vapor deposition. Deposition of polymers and resists can be performed by spin coating. SiO ₂ as the second insulating layer may be deposited by plasma enhanced chemical vapor deposition (PECVD). The etching of the second insulating layer and the metal conductive layer may be accomplished by ion milling, ion-coupled plasma (ICP) and reactive ion etching (RIE). The two-dimensional pattern of raised features of the metal conductive layer, and correspondingly, the pattern of assembled nanoelements, may be circles, triangles, rectangles, or dots as well as straight, curved, or intersecting linear features. It can be any pattern that can be built using lithographic techniques, including geometric shapes such as. The raised features may have a width in the range of about 10 nm to about 100 μm and a length of about 10 nm to several centimeters (eg, the entire diameter of the wafer).

Damasin template photography has a significant impact on the efficiency and yield of assembly and transfer processes. Ideally, flat photography is used that provides a uniform electric field centered from the edge of the electrodes, with minimal variation and facilitating a uniform assembly (see FIG. 6). 1 (c) shows a plot of simulated electric field intensities for various level differences (discing amount) between metal and insulator. As the amount of dishing increases, it is evident that the non-uniformity of the electric field from the edge of the electrodes also increases. In addition, non-flat photography can result in non-uniform transfer, resulting in recesses on the transfer substrate surface (see FIG. 7). In order to achieve flat photography, the endpoint detection of the CMP process needs to be precise [20]. For example, by determining the time period required for the CMP based on the associated material removal rate, sufficiently precise control can be achieved. A plan view and a cross-sectional view of the damascene template after CMP resulting in flat photography is shown in FIG. 1 (a). Along with the high resolution SEM images shown as insets, an optical image of a 3 inch damascene template is shown in FIG. 1 (b).

From Fig. 1 (c) it is clear that the electric field strengths close to the insulator and the electrode have about the same magnitude. In addition, any organic decontamination process, such as cleaning with a piranha solution (solution comprising a mixture of H ₂ SO ₄ and H ₂ O ₂ ), can increase the surface energy of the metal and the surface energy of the insulator. During the electrophoretic assembly process, the substantial electric field near the SiO ₂ surface bonded with SiO ₂ with high surface energy can result in nanoelement assembly onto the even unwanted SiO ₂ surface (see FIG. 8).

In particular, in order to assemble the nanoelements on the gold electrode surface, the electric field strength and its surface energy near the SiO ₂ surface must be reduced. Reducing the electric field strength through the application of a lower voltage will also reduce the electric field near the gold surface, which severely affects the assembly of nanoelements on the gold electrode. Alternatively, the assembly can be achieved specifically on gold electrodes if the surface energy of SiO ₂ is reduced without affecting the electric field of the electrode. To significantly reduce the surface energy of the SiO ₂ surface, self-assembled monolayers (SAMs) can be used. A preferred material for preparing SAM for coating the exposed surfaces of the SiO ₂ second insulating layer is octadecyltrichlorosilane (OTS); OTS can be used to modify the surface energy of the SiO ₂ layer without affecting the surface energy of raised gold features. Application of a SAM consisting essentially of OTS increased the contact angle of SiO ₂ from an initial value of less than 10 ° to 100 °. A post treatment process was developed to selectively remove the physically attached OTS SAM layer from gold without disturbing the OTS SAM layer on the SiO ₂ surface (see FIG. 9).

2 shows an example of an assembly and transfer process using the damascene template of the present invention. Electrophoresis is used to achieve direct assembly of the nanoelements, while a transfer printing method is used to transfer the assembled nanoelements onto the surface of the flexible substrate. The surface-modified template is enclosed in a suspension containing evenly distributed nanoelements. The characteristics of the solution (eg the pH of the water soluble suspension) are adjusted so that the nanoelements have a charge (negative or positive). A DC voltage is applied between the damascene template (having the opposite polarity to the charge on the nanoelements) and the basic gold template acting as the counter electrode (having the opposite polarity to that of the damascene template). For example, the alkaline pH may cause the nanoelements to be negatively charged, the damascene template may be positively charged, and the counter electrode may be negatively charged. The voltage is applied for a short period of time, typically less than one minute (eg, for a 20 second time period). Charged nanoelements are selectively assembled on the electrode surface and are not assembled on the insulator. With the potential still applied, after assembly, the template and counter electrode are withdrawn from the suspension at a constant rate. It is important to allow dislocations to be applied during withdrawal because, if no dislocations are applied, the hydrodynamic drag on the assembled nanoparticles is strong enough to remove the assembled nanoparticles [21]. Typical assembly results for nanoparticle assembly are shown in FIGS. 3 (b)-3 (d).

Given the charge on the nanoelements, the voltage applied between the template and the counter electrode dominates the assembly efficiency of the nanoelements (see FIG. 10). For low voltages, the electric field strength at the electrode edges is strong enough to attract and assemble nanoelements, while not at the center and thus no assembly occurs. Also, the withdrawal speed affects assembly efficiency (see FIG. 11). As shown in FIG. 3 (a), when a potential of 2 V was applied, 100 nm silica nanoparticles (suspended in deionized water at pH 10.8 adjusted by the addition of NH ₄ OH) were separated from the gold wires. Assembled only on the edges. Under these conditions, an extremely low draw rate (1 mm / min) can be used, so the dynamic drag force on the particles is minor. This is confirmed by the electric field contours simulated by the 3D finite volume modeling software (Flow 3D) shown in FIG.

As shown in FIG. 3 (b), when the applied potential is increased to 2.5 V, even at 5 mm / min pull out rate, 100 nm silica particles assemble in all of the regions across the electrodes in the damascene template. It became. (Iii) silica nanoparticles onto complex two-dimensional patterns (FIG. 3 (d)), (ii) 50 nm polystyrene-latex (PSL) particles (FIG. 3 (c)), and (iii) SWNT (FIG. 3). (e) By assembling the highly organized densities of the assembly of Figure 3 (f), the efficacy and material compatibility of the assembly process was demonstrated. For many applications, instead of random networks, highly ordered SWNTs are desirable because the ordered SWNTs block osmotic transfer paths and result in minimal junction resistance between tubes due to more surface area overlap. [22-24]. The alignment of the assembled SWNTs depends on the direction and speed of template withdrawal. Contrary to the increased assembly process time, lower draw rates lead to better alignment.

The damascene templates for assembling nanoelements can include both nanoscale and micron scale geometries and can use electrophoresis to induce direct assembly. That is, nanoscale and micron scale electrodes can be patterned on an insulator such that the nanoscale metal electrodes are connected to micron scale counterparts, and then the micron scale counterparts are large metal (as shown in FIG. 5 (a)). Is connected to the pad. During assembly using previous template designs, when a potential is applied to a large pad, there is a large potential drop across the length of the nanowires due to the increased resistance of the nanoscale features. This potential drop can have a significant impact on assembly results and can result in non-uniform assembly on various portions of the template. A typical result is shown in FIG. 5 (c) where the nanoparticle assembly occurs only on micron scale electrodes and not on nanoscale electrodes connected to the micron scale electrodes. However, using the damascene templates of the present invention, because all of the nanoscale and micron scale electrodes are connected to the metal sheet under the insulator (FIG. 5 (b)), when the potential is applied to the metal sheet during the nanoelement assembly, the micron There is a negligible variation in electrical potential between the scale electrode and the nanoscale electrode. Comparable resistor circuits are shown for both the conventional template as well as the damascene template.

Flow 3D software (v.10) from Flow Science, Inc. was used to simulate electric field contours for various template dimensions. The input parameters are: (i) applied voltage 2.5V, (ii) conductivity, (iii) pH 10.8, (iii) insulator thickness 150 nm, (iii) dielectric constants for insulator and solution (4 and 80, respectively) And (iii) mesh sizes 5 nm and 100 nm for distances less than 1 micron and distances greater than 1 micron, respectively. Effective field contours were generated at a distance of 25 nm from the surface. In FIG. 6 (a), the electric field simulation results for various non-flat photography of damascene templates are shown. As the photos flatten, the non-uniformity of the electric field strength across the metal electrode decreases. 6 (b) shows simulated results for a conventional template, where the nanoscale electrode is not connected to the underlying metal electrode. Due to morphology and photography variations, the non-uniformity of the electric field across the electrode is very pronounced, which can lead to assembly only at the edges of the electrode.

The assembled nanoelements were then transferred onto flexible polymer substrates (eg, PEN, PC) using a nanoimprint tool. The transfer efficiency of the transfer printing process is mainly determined by the differential adhesion between the subject (nanoelements) / template (ST) and the nanoelement / receptor (SR). If the adhesion between the nanoelement and the template, i.e., FST, is smaller than the adhesion between the nanoelement and the receiver, i.e., FSR, the nanoelements will be transferred onto the receiving surface. On the contrary, the nanoelements will stay on the template surface after the transfer process [18]. During the transfer, the OTS SAM hydrophobic coating on the SiO ₂ layer plays an additional role of the anti-stiction layer when the damascene template is separated from the flexible substrate during the transfer. This transfer process does not significantly affect the OTS layer, and thus does not significantly affect the surface energy of SiO ₂ , which means that the damascene template can be removed during the assembly-transfer cycle without additional surface modification for hundreds of cycles. Enable to be reused (see Figure 12). In addition, no additional processes such as striping, patterning, or sacrificial layer removal / deposition are needed.

In general, the contact angle of the polymer films used to coat the second insulating layer is ˜70 °, which is hydrophobic and thus very close to low surface energy. In order to improve the adhesion (FST) between the assembled nanoelements and the polymer film, the polymer film is pretreated using an oxygen plasma in an inductively coupled plasma island before the transfer printing process is performed. It became. This procedure results in the formation of hydroxide groups on the polymer surface, thereby increasing the surface energy of the polymer film [25] [26]. After surface treatment, the contact angle of the polymer film was found to be less than 5 °. During the transfer printing process of the present invention, a process temperature of about 160 ° C. was maintained and at the same time a pressure of 170 psi was used. This temperature is slightly higher than the glass transition temperature of the polymer film (155 ° C for PET, 150 ° C for PC), and is required to enclose the assembled nanoelements, so that full transfer can be achieved [19]. (See Figure 13). To measure the electrical characteristics of these transferred SWNTs, metal electrodes were fabricated by standard microfabrication processes. 4 (c) shows I-V measurements of SWNTs (2.4 μm channel width) transferred on PEN film as a function of channel length. The measured resistances were 3.2 kPa and 12.2 kPa, for the 2 μm and 17 μm channel lengths, respectively. 4 (d) shows the robustness of the assembled SWNT structure in the bent state. The resistance increases linearly as a function of the bending radius, with a maximum change of 13% compared to the bending radius of the initial value (see FIG. 14).

During the transfer of assembled nanoelements, using a template with non-flat photography (ie, having raised metal features) onto a flexible substrate, the transfer can be expected to be partial rather than whole. Another possible result is the generation of structures (replica of the template) imprinted on the flexible substrate. In many cases, this is not the desired result because subsequent processing (metal deposition, etching, etc.) can yield devices with non-uniform properties. Such observations using non-flat photography damascene templates are shown in FIG. 7.

When electrophoretic assembly was performed without the OTS SAM layer on the exposed surfaces of the second insulating layer, the nanoelements were assembled everywhere, including the conductor zone (electrode) as well as the insulator zone. Without the OTS SAM layer, the surface energies of the insulator and the electrode are approximately the same as shown in Figure 8 (a). When a potential is applied to the metal sheet under the insulator, the potential drop across the insulator is insufficient to prevent the nanoelement assembly, thus the nanoelements are assembled on the insulator, thereby reducing the selectivity of the assembly result. Typical results for the nanoparticle and SWNT assembly without the OTS SAM layer are shown in FIG. 8 (b).

Using wet chemical methods, an OTS SAM layer is applied to the damascene template. During this process, an OTS SAM layer can also be formed on the metal electrodes, and the OTS SAM layer can prevent nanoelements from being assembled on the metal electrodes. In order to selectively remove the OTS SAM layer from the metal electrode, chemical treatment with a "pyrana solution" was performed on the damascene template. Pirana treatment only removed the OTS SAM that was on the metal electrodes, leaving the monolayer on the insulator unaffected. This was verified through contact angle measurements as shown in FIG. 9 after OTS SAM layer deposition on the damascene template, before and after the pyranha treatment.

SWNTs used for assembly have terminal carboxylic acid groups due to their purification process. When suspended in deionized water, these carboxylic acid groups carry a negative charge on the SWNTs at a sufficiently high pH. The electrophoretic force on the nanoelements due to the applied potential is directly proportional to the charge and electric field strength on the nanoelements. As the applied voltage is increased, the electrophoretic force increases proportionally, resulting in increased amounts of nanoelements assembled on the metal electrodes. 9 clearly shows the significant effect of voltage on the SWNT assembly. From these results, it can be seen that the assembly of SWNTs on the electrodes started between 1.5V and 2V. If the threshold value of the applied potential is exceeded, the barrier introduced by SiO ₂ is broken and nanoelements can be assembled on the insulator surfaces as shown in FIG. 10.

During each withdrawal from the suspension after assembly, the capillary forces exerted on the assembled nanoelements play a decisive role in the adhesion of the nanoelements to the metal electrodes on the damascene template. For higher withdrawal rates, the removal moment applied to the nanoelements due to capillary force will be greater, resulting in removal of the nanoelements. For a given type of nanoelement and applied potential, the withdrawal speed needs to be adjusted and can be characterized as illustrated in FIG. By maintaining the applied potential, the adhesion can be further improved. In all of these experimental results shown herein, the potential was maintained during the template withdrawal process.

If the OTS SAM layer degrades on insulator surfaces, failure of the assembly and transfer process using damascene templates after several assembly and transfer cycles will be expected. If the OTS SAM on the insulator deteriorates, nanoelements can be assembled on the insulator, resulting in low yield. To test the versatility and robustness of damascene templates, the contact angle of the insulator surface after each assembly and transfer cycle was measured and it is plotted in FIG. 12. Extrapolation of these results based on the assumption that the OTS SAM layer degrades at the same rate in subsequent assembly and transfer cycles, the contact angle will reach a value of 70 ° after 140 cycles, while the contact angle is about 250 cycles. Induce an estimate that will reach a value of 50 ° at. In addition, the contact angle of the metal electrode will increase as a function of the number of periods and will eventually saturate. Assuming a saturation contact angle is a value of 50 °, the life cycle for a single coat of the OTS SAM layer will be about 250 cycles. If the OTS SAM layer has degraded, another layer of the OTS SAM layer can be added to the template and the other layer of the OTS SAM layer can be reused again for assembly and transfer.

The temperature applied to the substrates during the transfer process has a significant impact on the transfer efficiency. The transfer process temperature is preferably close to that of the glass transition temperature of the polymer forming the receiving substrate. This is demonstrated in FIG. 13. From the figure, it is clear that when the process temperature rises above Tg in the case of PEN (155 ° C.), the assembled nanoelements are transferred completely, essentially achieving 100% transfer yield.

Flexible receiving substrates with transferred nanoelements undergo a bending test. Cylindrical objects such as those shown in the inset of FIG. 14 were used for the bending test. A PEN film with transferred SWNTs and deposited electrodes was taped around the cylindrical object and resistance measurements were taken while bent. The results are shown in FIG.

As used herein, "consisting essentially of" does not exclude materials or steps that do not significantly affect the basic and novel features of the claims. In particular in the description of the components of the composition or in the description of the elements of the device, any reference herein to the term "comprising" may be exchanged for "consisting essentially of" or "consisting of".

Although the present invention has been described in conjunction with certain preferred embodiments, those skilled in the art, after reading the foregoing specification, may make various changes, substitutions in equivalents, and other modifications to the compositions and methods disclosed herein. There will be.

Cited References

[1] T. Kraus, L. Malaquin, H. Schmid, W. Riess, N. D. Spencer, H. Wolf, Nature nanotechnology 2007, 2, 570.

[2] C. Yilmaz, T. H. Kim, S. Somu, A. A. Busnaina, Nanotechnology, IEEE Transactions on 2010, 9, 653.

[3] R. Krupke, F. Hennrich, H. Weber, M. Kappes, H. Lohneysen, Nano letters 2003, 3, 1019.

[4] P. Maury, M. Escalante, D. N. Reinhoudt, J. Huskens, Advanced Materials 2005, 17, 2718.

[5] Y. Xia, Y. Yin, Y. Lu, J. McLellan, Advanced Functional Materials 2003, 13, 907.

[6] L. Jaber-Ansari, M. G. Hahm, S. Somu, Y. E. Sanz, A. Busnaina, Y. J. Jung, Journal of the American Chemical Society 2008, 131, 804.

[7] X. Xiong, P. Makaram, A. Busnaina, K. Bakhtari, S. Somu, N. McGruer, J. Park, Applied physics letters 2006, 89, 193108.

[8] R. C. Bailey, K. J. Stevenson, J. T. Hupp, Advanced Materials 2000, 12, 1930.

[9] Q. Zhang, T. Xu, D. Butterfield, M. J. Misner, Du Yoel Ryu, T. Emrick, T. P. Russell, Nano letters 2005, 5, 357.

[10] E. Kumacheva, R. K. Golding, M. Allard, E. H. Sargent, Advanced Materials 2002, 14, 221.

[11] B. Li, H. Y. Jung, H. Wang, Y. L. Kim, T. Kim, M. G. Hahm, A. Busnaina, M. Upmanyu, Y. J. Jung, Advanced Functional Materials 2011, 21, 1810.

[12] J. H. Ahn, H. S. Kim, K. J. Lee, S. Jeon, S. J. Kang, Y. Sun, R. G. Nuzzo, J. A. Rogers, science 2006, 314, 1754.

[13] Y. Sun, H. H. Wang, Advanced Materials 2007, 19, 2818.

[14] D. Lee, T. Cui, Biosensors and Bioelectronics 2010, 25, 2259.

[15] B. Li, M. G. Hahm, Y. L. Kim, H. Y. Jung, S. Kar, Y. J. Jung, ACS nano 2011, 5, 4826.

[16] M. A. Meitl, Z. T. Zhu, V. Kumar, K. J. Lee, X. Feng, Y. Y. Huang, I. Adesida, R. G. Nuzzo, J. A. Rogers, Nature Materials 2005, 5, 33.

[17] F. N. Ishikawa, H. Chang, K. Ryu, P. Chen, A. Badmaev, L. Gomez De Arco, G. Shen, C. Zhou, ACS nano 2008, 3, 73.

[18] D. Hines, V. Ballarotto, E. Williams, Y. Shao, S. Solin, Journal of applied physics 2007, 101, 024503.

[19] T. Tsai, C. Lee, N. Tai, W. Tuan, Applied physics letters 2009, 95, 013107.

[20] T. Bibby, K. Holland, Journal of electronic materials 1998, 27, 1073.

[21] S. Siavoshi, C. Yilmaz, S. Somu, T. Musacchio, J. R. Upponi, V. P. Torchilin, A. Busnaina, Langmuir 2011, 27, 7301.

[22] E. Artukovic, M. Kaempgen, D. Hecht, S. Roth, G. Gruner, Nano letters 2005, 5, 757.

[23] L. Hu, D. Hecht, G. Gruner, Nano letters 2004, 4, 2513.

[24] M. Fuhrer, J. Nygard, L. Shih, M. Forero, Y. G. Yoon, H. J. Choi, J. Ihm, S. G. Louie, A. Zettl, P. L. McEuen, science 2000, 288, 494.

[25] N. Inagaki, Plasma surface modification and plasma polymerization, CRC, 1996.

[26] E. Liston, L. Martinu, M. Wertheimer, Journal of adhesion science and technology 1993, 7, 1091.

Claims (46)

As a damascene template for electrophoretic assembly and transcription of patterned nanoelements,
A substantially planar substrate;
A first insulating layer disposed on a surface of the substrate;
An opposing adhesive layer disposed on the surface of the first insulating layer opposite the substrate;
A conductive metal layer disposed on the surface of the first insulating layer opposite the first insulating layer, or on the surface of the first insulating layer opposite the substrate, if the adhesive layer is absent;
A second insulating layer disposed on the surface of the conductive metal layer opposite the adhesive layer or opposite the first insulating layer if the adhesive layer is absent; And
A hydrophobic coating selectively disposed on exposed surfaces of the second insulating layer, opposite the conductive metal layer
Including,
The conductive metal layer is continuous over at least one zone of the substrate, and within the zone, the conductive metal layer has raised features of a two-dimensional microscale or nanoscale pattern that interrupts the second insulating layer; The second insulating layer substantially fills the spaces between the raised features; The exposed surfaces of the raised features and the exposed surfaces of the second insulating layer are essentially coplanar,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
Wherein the substrate comprises silicon or a polymer,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The substrate thickness is 1 μm to 10 μm,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
Wherein the first insulating layer comprises silicon dioxide, SiN ₄ or a polymer,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The first insulating layer thickness is 5 nm to 500 nm,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The adhesive layer comprises a material selected from the group consisting of chromium, titanium, titanium dioxide, titanium nitride, tantalum, tantalum nitride, tungsten, and combinations thereof
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The adhesive layer thickness is 3 nm to 50 nm,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The conductive metal layer comprises gold, silver, tungsten, aluminum, titanium, ruthenium, copper, or combinations thereof
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
Wherein the second insulating layer comprises a material selected from the group consisting of SiO ₂ , SiN ₄ , Al ₂ O ₃ , an organic polymer, and combinations thereof
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The second insulating layer has a thickness of 10 nm to 10 μm,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The conductive metal layer comprises a planar portion having a thickness of 50 nm to 100 μm,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The hydrophobic coating is a silane coating,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
Wherein said hydrophobic coating comprises a monolayer of alkyl silane molecules,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The hydrophobic coating comprises an octadecyltrichlorosilane (OTS),
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The contact angle of the hydrophobic coating is 90 ° to 110 °,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The contact angle of the hydrophobic coating is about 100 °,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The contact angle of exposed raised feature surfaces is between 15 ° and 21 °,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The contact angle of the exposed raised feature surfaces is about 18 °,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The heights of the raised features are essentially the same as the thickness of the second insulating layer,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The raised features include substantially linear features,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
Linear features may be straight, curved, intersecting, or forming a circle, triangle, or rectangle,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The raised features are 10 nm to 100 μm wide,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The raised features are 10 nm to 10 cm in length,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The raised features in one zone are in electrical contact with each other via the conductive metal layer,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The exposed surfaces of raised features are essentially free of the hydrophobic coating,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
The template is soft,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 1,
Further comprising a plurality of nanoelements non-covalently attached to the exposed surfaces of the raised features, wherein the exposed surfaces of the second insulating layer are essentially free of attached nanoelements,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 27,
The nanoelements are nanoparticles, single-walled carbon nanotubes, multi-walled carbon nanotubes, nanowires, nanofibers, pentacene molecules, fullerene molecules, or polymers,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. The method of claim 27,
Wherein the nanoelements are conductive, semi-conductive, or insulating,
A damascene template for electrophoretic assembly and transcription of patterned nanoelements. A nanoelement transfer system for the transfer of patterned nanoelements by nanoimprinting,
28. The damascene template of claim 27 and a flexible polymer substrate for receiving the plurality of nanoelements.
Nanoelement transcription system for transcription of patterned nanoelements by nanoimprinting. The method of claim 30,
The flexible polymer substrate may include polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene, polyethylene terephthalate (PET), polyimide, or a combination thereof.
Nanoelement transcription system for transcription of patterned nanoelements by nanoimprinting. The method of claim 30,
Thermally controlled imprint device for applying pressure between the damascene template and the flexible polymer substrate at a selected temperature above ambient temperature
Further comprising,
Nanoelement transcription system for transcription of patterned nanoelements by nanoimprinting. The method of claim 30,
The imprint device can operate at a temperature higher than the glass transition temperature of the flexible polymer substrate,
Nanoelement transcription system for transcription of patterned nanoelements by nanoimprinting. The method of claim 30,
The imprint device can apply a pressure of at least 170 psi at a temperature of at least 160 ° C. and between the damascene template and the flexible polymer substrate.
Nanoelement transcription system for transcription of patterned nanoelements by nanoimprinting. The method of claim 30,
The flexible polymer film has a contact angle of less than about 5 ° and the exposed surfaces of the raised features on the damascene template have a contact angle of about 18 °.
Nanoelement transcription system for transcription of patterned nanoelements by nanoimprinting. The method of claim 30,
The flexible polymer film is treated with an oxygen plasma such that the flexible polymer film becomes less hydrophobic,
Nanoelement transcription system for transcription of patterned nanoelements by nanoimprinting. A method for producing the damascene template of claim 1,
(a) providing a substantially planar substrate;
(b) depositing a first insulating layer on the surface of the substrate;
(c) optionally, depositing an adhesive layer on said first insulating layer;
(d) depositing a conductive metal layer on the adhesive layer or on the first insulating layer if the adhesive layer is absent;
(e) depositing a lithographic resist layer on the conductive metal layer;
(f) performing lithography to produce voids in the resist layer in a two-dimensional pattern, whereby the surface of the conductive metal layer is exposed at the voids;
(g) etching the exposed surface of the conductive metal layer;
(h) removing the resist layer, leaving the entire surface of the conductive metal layer exposed, wherein the conductive metal layer includes raised features in a two-dimensional pattern;
(i) depositing an insulating material to cover the conductive metal layer including the raised features;
(j) removing the insulating material and a portion of the raised features by a chemical mechanical polishing method, whereby the raised features and insulating material are planarized to expose the raised features of the two-dimensional pattern Left exposed, the exposed surfaces being coplanar with each other and with the exposed surfaces of the insulating material; And
(k) selectively silanizing exposed surfaces of the insulating material using a hydrophobic coating of alkyl silanes
Including,
A method of making the damascene template of claim 1. The method of claim 37,
(l) chemically cleaning the exposed surfaces of the raised features of the conductive metal layer without substantially removing the hydrophobic coating on the insulating layer
Further comprising,
A method of making the damascene template of claim 1. A method of forming a patterned assembly of nanoelements on a damascene template,
(a) providing the damascene template of claim 1;
(b) dipping the damascene template into the liquid suspension of nanoelements;
(c) in the liquid suspension, applying a voltage between the conductive metal layer of the damascene template and the counter electrode, such that nanoelements from the suspension are formed of raised features of the conductive metal layer of the damascene template. Selectively assembled onto exposed surfaces and not assembled onto exposed surfaces of the second insulating layer of the damascene template;
(d) withdrawing the damascene template and the assembly of nanoelements from the liquid suspension while continuing to apply the same voltage as in step (c); And
(e) drying the damascene template
Including,
A method of forming a patterned assembly of nanoelements on a damascene template. The method of claim 39,
During steps (c) and (d), the conductive metal layer of the damascene template is positive, the counter electrode is negative, and the pH of the liquid suspension is adjusted so that the nanoelements have a negative charge.
A method of forming a patterned assembly of nanoelements on a damascene template. The method of claim 39,
During steps (c) and (d), the conductive metal layer of the damascene template is negative, the counter electrode is positive, and the pH of the liquid suspension is adjusted such that the nanoelements have a positive charge.
A method of forming a patterned assembly of nanoelements on a damascene template. The method of claim 39,
The voltage applied in steps (c) and (d) is high enough to provide an assembly over essentially the entire exposed surface of the raised features of the conductive metal layer of the damascene template,
A method of forming a patterned assembly of nanoelements on a damascene template. The method of claim 39,
The rate of withdrawing the damascene template in step (d) is slow enough to maintain a patterned assembly of nanoelements on the surface of the raised features of the conductive metal layer of the damascene template through a withdrawal process.
A method of forming a patterned assembly of nanoelements on a damascene template. The method of claim 39,
The voltage in steps (c) and (d) is in the range of 1.5 V to 7 V, and the withdrawal speed in step (d) is in the range of 1 mm / min to 15 mm / min,
A method of forming a patterned assembly of nanoelements on a damascene template. A method of assembling and transferring a two-dimensional patterned assembly of nanoelements onto a flexible polymer substrate,
(a) providing a nanoelement transfer system of claim 30 and a liquid suspension of nanoelements;
(b) performing electrophoretic assembly of nanoelements from the liquid suspension according to the method of claim 39 to yield a patterned assembly of nanoelements on a damascene template;
(c) contacting and applying the patterned assembly of nanoelements to the flexible polymer substrate, whereby the patterned assembly of nanoelements is transferred onto a flexible patterned substrate.
Including,
Step (c) is carried out at a temperature above the glass transition temperature of the flexible polymer substrate,
A method of assembling and transferring a two-dimensional patterned assembly of nanoelements onto a flexible polymer substrate. A method of transferring a two-dimensional patterned assembly of nanoelements onto a flexible polymer substrate,
(a) providing a two-dimensional patterned assembly of nanoelements on a damascene template, and a flexible polymer substrate;
(b) contacting and applying the patterned assembly of nanoelements to the flexible polymer substrate, whereby the patterned assembly of nanoelements is transferred onto a flexible patterned substrate.
Including,
The contacting is carried out at a temperature above the glass transition temperature of the flexible polymer substrate,
A method of transferring a two-dimensional patterned assembly of nanoelements onto a flexible polymer substrate.

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